Libksba

Libksba is a library to make the tasks of working with
X.509 certificates, CMS data and related objects more easy. It
provides a highlevel interface to the implemented protocols and presents
the data in a consistent way. There is no more need to worry
about all the nasty details of the protocols. The API gives the
C programmer an easy way of interacting with the data. It copes
with the version details X.509 protocols tend to have as well as
with the many different versions and dialects. Applications
must usually cope with all of this and it has to be coded over
and over again. Libksba hides this by providing just one
API which does the Right Thing. Support for new features will
be added as needed.